JP6908031B2 - Redox flow battery cells, redox flow battery cell stacks, and redox flow batteries - Google Patents

Description

The present invention relates to a redox flow battery cell, a redox flow battery cell stack, and a redox flow battery.

As one of the large-capacity storage batteries, there is a redox flow battery (hereinafter, sometimes referred to as "RF battery") in which an electrolytic solution is circulated and circulated through positive and negative electrodes arranged across a diaphragm to charge and discharge. It is known (see Patent Document 1). Patent Document 1 discloses a cell stack in which a plurality of cell frames, positive electrodes, diaphragms (ion exchange membranes), and negative electrodes are laminated. The cell frame includes a frame body and a bipolar plate integrated with the frame body. In this cell stack, positive and negative electrodes are arranged across a diaphragm between the bipolar plates of adjacent cell frames to form one cell.

Japanese Unexamined Patent Publication No. 2012-99368

The redox flow battery cell of the present disclosure is
A redox flow battery cell including a positive electrode, a negative electrode, and a diaphragm interposed between the positive electrode and the negative electrode.
It has an overlapping region in which the positive electrode and the negative electrode overlap via the diaphragm, and a non-overlapping region in which at least one of the positive electrode and the negative electrode does not overlap via the diaphragm.
The total area of the non-overlapping region is 0.1% or more and 20% or less of the area of the overlapping region.

The redox flow battery cell stack of the present disclosure is
A plurality of the above-mentioned redox flow battery cells of the present disclosure are stacked and provided.

The redox flow battery of the present disclosure is
The redox flow battery cell of the present disclosure or the redox flow battery cell stack of the present disclosure is provided.

It is an operation principle figure of the redox flow battery which concerns on embodiment. It is a schematic block diagram of the redox flow battery which concerns on embodiment. It is a schematic block diagram of the cell stack which concerns on embodiment. It is the schematic plan view which looked at the cell frame provided with the cell stack which concerns on embodiment from one side. It is a schematic plan view which shows an example of the arrangement form of the positive electrode and the negative electrode in the cell which concerns on embodiment transparently.

[Issues to be solved by this disclosure]
It is desired that RF batteries can be restarted by themselves in the event of a power failure in the power system.

In an RF battery, an electrolytic solution is circulated by a pump in a cell arranged so that a positive electrode and a negative electrode face each other with a diaphragm in between, and charging / discharging is performed. Generally, in an RF battery, power is supplied to a pump from an external power system to drive the pump. Therefore, when the power system loses power, the pump stops and the flow of the electrolytic solution stops, so that even if the RF battery wants to discharge to the power system, it cannot be discharged. Therefore, in order to enable the operation of the RF battery to be restarted by itself in the event of a power failure in the power system, it is required to supply the power required for starting the pump from the cell (or cell stack).

With RF batteries, even if the pump stops during a power system power failure, the electrolyte remains in the cell, so the pump is started using the power generated by the discharge of the electrolyte between the positive and negative electrodes in the cell. It is possible to do. However, in a cell in a conventional RF battery, the areas of both positive and negative electrodes are usually the same, and the entire surfaces of both electrodes are arranged so as to overlap each other with a diaphragm in between. A reaction occurs. Therefore, in a conventional cell, for example, when a power system power failure occurs when the RF battery is discharged, the electrolytic solution in the cell is discharged due to the discharge reaction, so that the electrolytic solution remaining in the cell pumps. It may not be possible to secure enough power to start up. In addition, the self-discharge of the electrolytic solution easily progresses between both electrodes, and the power stored in the electrolytic solution in the cell is easily consumed by the self-discharge while the pump is stopped. Therefore, the pump stops due to a power failure of the power system. The time constraint from the start of the pump to the start of the pump is strict.

Therefore, one of the objects of the present disclosure is to provide a redox flow battery cell and a redox flow battery cell stack capable of supplying electric power for starting a pump in the event of a power failure of an electric power system. Another object of the present disclosure is to provide a redox flow battery capable of restarting operation by itself in the event of a power failure of the electric power system.

[Effect of the present disclosure]
According to the present disclosure, it is possible to provide a redox flow battery cell and a redox flow battery cell stack capable of supplying electric power for starting a pump in the event of a power failure of an electric power system. Further, according to the present disclosure, it is possible to provide a redox flow battery capable of restarting operation by itself in the event of a power failure of the electric power system.

[Explanation of Embodiments of the Invention]
First, the contents of the embodiments of the present invention will be listed and described.

(1) The redox flow battery cell according to the embodiment is
A redox flow battery cell including a positive electrode, a negative electrode, and a diaphragm interposed between the positive electrode and the negative electrode.
It has an overlapping region in which the positive electrode and the negative electrode overlap via the diaphragm, and a non-overlapping region in which at least one of the positive electrode and the negative electrode does not overlap via the diaphragm.
The total area of the non-overlapping region is 0.1% or more and 20% or less of the area of the overlapping region.

In the redox flow battery cell, both electrodes are arranged so as to have an overlapping region and a non-overlapping region between the positive electrode and the negative electrode, and the total area of the non-overlapping regions in both electrodes is 0. It is 1% or more and 20% or less. The “overlapping region” is a region in which the positive electrode and the negative electrode overlap each other when the positive electrode and the negative electrode are viewed through from one side. On the other hand, the "non-overlapping area" is an area that does not overlap with each other, excluding the overlapping area. The overlapping region is a portion that contributes to the battery reaction between the two electrodes, and the non-overlapping region is a portion that does not contribute to the battery reaction between the two electrodes.

According to the redox flow battery cell, at least one of the positive electrode and the negative electrode has a non-overlapping region. Since the non-overlapping region does not contribute to the battery reaction, there is an unreacted electrolyte solution that has not reacted with the battery in the non-overlapping region. That is, when the pump is stopped and the flow of the electrolytic solution is stopped at the time of power failure of the power system, the unreacted electrolytic solution remains in a part of the cell. Then, while the pump is stopped, the unreacted electrolyte existing in the non-overlapping region diffuses into the overlapping region, so that the electric power required for starting the pump can be supplied from the cell by the discharge between both electrodes. It becomes. Therefore, for example, even if the power system power failure occurs when the RF battery is discharged and the pump is stopped, the power required to start the pump by the undischarging electrolytic solution existing in the non-overlapping region in the cell is used. Can be secured. Further, even if the self-discharge of the electrolytic solution progresses in the overlapping region between the two electrodes while the pump is stopped, the unreacted electrolytic solution existing in the non-overlapping region diffuses into the overlapping region, so that unreacted electrolysis occurs. The electric power stored in the liquid can be discharged for a long period of time. Therefore, the time constraint from the stop of the pump to the start of the pump due to the power failure of the power system can be relaxed. Therefore, the redox flow battery cell can supply power to start the pump in the event of a power failure in the power system, and can start the pump even when there is no power supply to the pump from the outside. Become.

In the above-mentioned redox flow battery cell, the total area of the non-overlapping areas is 0.1% or more of the area of the overlapping areas, so that the amount of electrolytic solution flowing in the non-overlapping areas can be secured, and the pump can be used in the event of a power failure. It is easy to secure the power required for startup. On the other hand, the larger the area ratio of the non-overlapping regions, the larger the ratio of the electrolytic solution flowing in the non-overlapping regions, and the smaller the amount of the electrolytic solution flowing in the overlapping regions. When the total area of the non-overlapping regions is 20% or less of the area of the overlapping regions, it is possible to secure the overlapping regions that contribute to the battery reaction and suppress a decrease in output during charging / discharging.

(2) As one form of the redox flow battery cell, both the positive electrode and the negative electrode have the non-overlapping region.

Since both the positive electrode and the negative electrode have a non-overlapping region, an unreacted electrolytic solution exists in the non-overlapping region of each electrode. Therefore, the electrolytic solution can be reliably discharged between the two electrodes, and the power required for starting the pump can be supplied in the event of a power failure of the power system to reliably start the pump.

(3) As one form of the redox flow battery cell, the areas of the positive electrode and the negative electrode are the same.

When the areas of the positive electrode and the negative electrode are the same, a non-overlapping region having the same area is formed on both the positive electrode and the negative electrode, and the amount of the electrolytic solution flowing in the non-overlapping region of each electrode is equal. Therefore, the electrolytic solution can be sufficiently discharged between the two electrodes, and sufficient power required for starting the pump can be supplied in the event of a power failure of the power system. "The area of the positive electrode and the negative electrode are the same" means that the areas of both electrodes are substantially the same. For example, when the difference between the areas of both electrodes is 0.01% or less of each area. If there is, it is considered to be the same area. Here, each area of the positive electrode and the negative electrode is the plane area of the surfaces of the electrodes facing each other.

(4) As one form of the redox flow battery cell, the thickness of the positive electrode and the negative electrode is 0.05 mm or more.

When the thickness of both electrodes is 0.05 mm or more, it is easy to secure a sufficient amount of the electrolytic solution flowing in the non-overlapping region. Therefore, it is easy to secure sufficient power required to start the pump in the event of a power failure of the power system. Here, each thickness of the positive electrode and the negative electrode is the thickness of each electrode in the state of being arranged in the cell, and when the electrodes are housed in the cell in the compressed state, it is in the compressed state. The thickness.

(5) As one form of the redox flow battery cell, the area of the positive electrode and the negative electrode is 250 cm ² or more.

When the area of both electrodes is 250 cm ² or more, it is easy to sufficiently secure the respective areas of the overlapping region and the non-overlapping region, and it is easy to sufficiently secure the amount of the electrolytic solution flowing in each region. Therefore, it is easy to secure the output at the time of charging / discharging and sufficiently secure the power required for starting the pump in the event of a power failure of the power system.

(6) The redox flow battery cell stack according to the embodiment is
A plurality of redox flow battery cells according to any one of (1) to (5) above are stacked and provided.

By including the redox flow battery cell according to the above embodiment, the redox flow battery cell stack can supply electric power to start the pump in the event of a power failure of the power system. The redox flow battery cell stack includes a plurality of cells, and the electric power required to start the pump can be secured by the unreacted electrolyte existing in the non-overlapping region in each cell. Therefore, it is possible to sufficiently supply the electric power required for starting the pump from the cell stack.

(7) The redox flow battery according to the embodiment is
The redox flow battery cell according to any one of (1) to (5) above, or the redox flow battery cell stack according to (6) above is provided.

By including the redox flow battery cell or the redox flow battery cell stack according to the above embodiment, the redox flow battery can supply the power required for starting the pump from the cell or the cell stack in the event of a power failure of the power system. It is possible to start the pump. Therefore, according to the redox flow battery, it is possible to restart the operation by itself in the event of a power failure of the power system.

[Details of Embodiments of the present invention]
A redox flow battery cell (hereinafter, may be simply referred to as a “cell”), a redox flow battery cell stack (hereinafter, may be simply referred to as a “cell stack”), and a redox flow battery (RF) according to an embodiment of the present invention. A specific example of the battery) will be described below with reference to the drawings. The same reference numerals in the figure indicate the same or corresponding parts. It should be noted that the present invention is not limited to these examples, and is indicated by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

《RF battery》
An example of the RF battery 1 according to the embodiment, and the cell 100 and the cell stack 2 provided in the RF battery 1 will be described with reference to FIGS. 1 to 5. The RF battery 1 shown in FIGS. 1 and 2 uses an electrolytic solution containing a metal ion whose valence changes due to oxidation-reduction in the positive electrode electrolytic solution and the negative electrode electrolytic solution as an active material, and the ions contained in the positive electrode electrolytic solution. It is a battery that charges and discharges by utilizing the difference between the oxidation-reduction potential and the oxidation-reduction potential of ions contained in the negative electrode electrolyte. FIG. 1 shows a vanadium-based RF battery in which a vanadium electrolytic solution containing V ions as an active material is used in the positive electrode electrolytic solution and the negative electrode electrolytic solution as an example of the RF battery 1. The solid line arrow in the cell 100 in FIG. 1 indicates the charge reaction, and the broken line arrow indicates the discharge reaction. The RF battery 1 is connected to the power system L via an AC / DC converter C, and is used, for example, for load leveling applications, applications such as instantaneous low compensation and emergency power supply, and photovoltaic power generation, which is being introduced in large quantities. It is used for smoothing the output of natural energy such as wind power generation.

"cell"
The RF battery 1 includes a cell 100 including a positive electrode 104, a negative electrode 105, and a diaphragm 101 interposed between the positive electrode 104 and the negative electrode 105 (see FIG. 1). The structure of the cell 100 shown in this example is separated into a positive electrode cell 102 and a negative electrode cell 103 by a diaphragm 101 that allows hydrogen ions to permeate, and a positive electrode 104 is built in the positive electrode cell 102 and a negative electrode 105 is built in the negative electrode cell 103. ing. A positive electrode electrolyte tank 106 for storing the positive electrode electrolyte is connected to the positive electrode cell 102 via conduits 108 and 110. The conduit 108 is provided with a pump 112 for circulating the positive electrode electrolytic solution from the positive electrode electrolytic solution tank 106 to the positive electrode cell 102, and the positive electrode circulation for circulating the positive electrode electrolytic solution by these members 106, 108, 110, 112. The mechanism 100P is configured. Similarly, a negative electrode electrolytic solution tank 107 for storing the negative electrode electrolytic solution is connected to the negative electrode cell 103 via conduits 109 and 111. The conduit 109 is provided with a pump 113 for circulating the negative electrode electrolytic solution from the negative electrode electrolytic solution tank 107 to the negative electrode cell 103, and the negative electrode circulating solution is circulated by these members 107, 109, 111, 113. The mechanism 100N is configured. During the charge / discharge operation, the pumps 112 and 113 are driven, and the positive and negative electrolytes flow into the cells 100 (positive electrode cell 102 and negative electrode cell 103). During the standby period when the charge / discharge is not performed, the pumps 112 and 113 Stops, and the flow of each electrolyte stops. In this example, during normal operation, power is supplied from the power system L to the pumps 112 and 113 to drive the pumps 112 and 113.

《Cell stack》
As shown in FIGS. 2 and 3, the RF battery 1 shown in this example includes a cell stack 2 in which a plurality of cells 100 are stacked. The cell stack 2 is configured by sandwiching a laminate called a sub-stack 200 (see FIG. 3) between two end plates 220 from both sides thereof, and tightening the end plates 220 on both sides by a tightening mechanism 230 (FIG. 3). The configuration illustrated in 3 includes a plurality of sub-stacks 200). The sub-stack 200 is formed by laminating a plurality of cell frames 3, positive electrode 104, diaphragm 101, and negative electrode 105, and supply / discharge plates 210 (see the lower figure of FIG. 3, omitted in FIG. 2) are provided at both ends of the laminated body. It is an arranged configuration. The number of stacked cells 100 in the cell stack 2 is, for example, 5 or more, 50 or more, and 100 or more. The upper limit of the number of stacked cells 100 is not particularly limited, but is, for example, 200 or less.

《Cell frame》
As shown in FIGS. 2 and 3, the cell frame 3 has a bipolar plate 31 arranged between the positive electrode 104 and the negative electrode 105, and a frame 32 provided around the bipolar plate 31. The positive electrode 104 is arranged so as to be in contact with one surface side of the bipolar plate 31, and the negative electrode 105 is arranged so as to be in contact with the other surface side of the bipolar plate 31. A bipolar plate 31 is provided inside the frame body 32, and a recess 32o is formed by the bipolar plate 31 and the frame body 32 (see also FIG. 4). The recesses 32o are formed on both sides of the bipolar plate 31 (front side and back side of the paper surface in FIG. 4), and the positive electrode 104 and the negative electrode 105 are housed in the recesses 32o with the bipolar plate 31 interposed therebetween. In the sub-stack 200 (cell stack 2), one side and the other side of the frame 32 of each adjacent cell frame 3 are opposed to each other and abutted against each other, and are placed between the bipolar plates 31 of the adjacent cell frames 3, respectively. One cell 100 will be formed.

The bipolar plate 31 is made of, for example, plastic carbon, and the frame 32 is made of, for example, a plastic such as vinyl chloride resin (PVC), polypropylene, polyethylene, fluororesin, or epoxy resin. The bipolar plate 31 is formed by a known method such as injection molding, press molding, or vacuum forming. In the cell frame 3 shown in this example, the frame body 32 is integrated around the bipolar plate 31 by injection molding or the like. In this example, the planar shape (shape when viewed in a plan view) of the bipolar plate 31 is rectangular, and the shape of the frame 32 is rectangular.

The flow of the electrolytic solution to the cell 100 is carried out through the supply / drain plate 210 (see the lower figure of FIG. 3), the liquid supply manifolds 33, 34 and the liquid supply manifolds 33, 34 provided so as to penetrate the frame body 32 of the cell frame 3 shown in FIG. This is performed by the drainage manifolds 35 and 36, and the liquid supply slits 33s and 34s and the drainage slits 35s and 36s formed in the frame 32 (see also FIG. 4). In the case of the cell frame 3 (frame body 32) shown in this example, the positive electrode electrolytic solution is formed on one side (front side of the paper surface in FIG. 4) of the frame body 32 from the liquid supply manifold 33 provided at the lower part of the frame body 32. It is supplied to the positive electrode 104 through the liquid supply slit 33s, and is discharged to the drainage manifold 35 via the drainage slit 35s formed on the upper portion of the frame 32. Similarly, the negative electrode electrolyte solution is supplied from the liquid supply manifold 34 provided at the lower part of the frame body 32 to the negative electrode electrode via the liquid supply slit 34s formed on the other surface side (the back side of the paper surface in FIG. 4) of the frame body 32. It is supplied to 105 and discharged to the drainage manifold 36 through the drainage slit 36s formed on the upper portion of the frame body 32. A rectifying portion (not shown) may be formed along the edge portion on the inner lower edge portion and the upper edge portion of the frame body 32 on which the bipolar plate 31 is provided. The rectifying unit diffuses the electrolytic solutions supplied from the liquid supply slits 33s and 34s along the lower edges of the electrodes 104 and 105, and discharges the electrolytic solutions from the upper edges of the electrodes 104 and 105. Has a function of concentrating the liquid in the drainage slits 35s and 36s.

In the cell 100 shown in this example, the electrolytic solution is supplied from the lower side of the positive electrode 104 and the negative electrode 105, respectively, and the electrolytic solution is discharged from the upper side of each of the electrodes 104 and 105. The electrolytic solution flows from the lower edge portion to the upper edge portion of the 105 (in FIG. 4, the thick line arrow on the left side of the paper indicates the overall flow direction of the electrolytic solution of the electrolytic solution). A plurality of grooves (not shown) may be formed on the surface of the bipolar plate 31 in contact with the electrodes 104 and 105 along the flow direction of the electrolytic solution. As a result, the flow resistance of the electrolytic solution can be reduced, and the pressure loss of the electrolytic solution can be reduced. The cross-sectional shape of the groove (the shape of the cross section orthogonal to the flow direction of the electrolytic solution) is not particularly limited, and examples thereof include a rectangular shape, a triangular shape (V-shape), a trapezoidal shape, a semicircular shape, and a semi-elliptical shape. Be done.

In addition, an annular sealing member 37 (see FIGS. 2 and 3) such as an O-ring or flat packing is arranged between the frame bodies 32 of each cell frame 3 in order to suppress leakage of the electrolytic solution. A seal groove 38 (see FIG. 4) for arranging the seal member 37 is formed in the frame body 32.

One of the features of the cell 100 according to the embodiment is the arrangement of the positive electrode 104 and the negative electrode 105 which are arranged so as to face each other with the diaphragm 101 interposed therebetween. Specifically, the overlapping region OA in which the positive electrode 104 and the negative electrode 105 overlap via the diaphragm 101, and the non-overlapping region SA in which at least one of the positive electrode 104 and the negative electrode 105 does not overlap via the diaphragm 101. Has (see FIG. 5). Hereinafter, the arrangement form of the positive electrode 104 and the negative electrode 105 in the cell 100 will be described with reference mainly to FIG. In FIG. 5, the diaphragm is omitted.

<< Positive electrode and negative electrode >>
The positive electrode 104 and the negative electrode 105 are reaction fields in which the active material (ions) contained in the electrolytic solution undergoes a battery reaction. Each of the electrodes 104 and 105 can be formed of a known material, for example, a non-woven fabric (carbon felt) or woven fabric (carbon cloth) made of carbon fiber, paper (carbon paper), or the like. In this example, the planar shapes of the electrodes 104 and 105 are rectangular.

The thickness of each of the electrodes 104 and 105 is not particularly limited, and examples thereof include 0.05 mm and more, and further 0.2 mm and more. When the thickness of each of the electrodes 104 and 105 is 0.05 mm or more, it is easy to secure the amount of the electrolytic solution flowing through each of the electrodes 104 and 105 and secure the output at the time of charging and discharging. The thicknesses of the electrodes 104 and 105 referred to here are the thicknesses of the cells 100 (see FIG. 3) in an assembled state, and the electrodes 104 and 105 are located in the cell 100 (recess 32o of the cell frame 3). When it is stored in a compressed state in the thickness direction, it is the thickness in the compressed state. In this case, the depth of the recess 32o corresponds to the thickness of each of the electrodes 104 and 105. The upper limit of the thickness of each of the electrodes 104 and 105 is, for example, 3.0 mm or less.

The area of each of the electrodes 104 and 105 is not particularly limited, but may be, for example, 250 cm ² or more, and further 500 cm ² or more. Since the area of each of the electrodes 104 and 105 is 250 cm ² or more, it is easy to secure the amount of the electrolytic solution flowing through each of the electrodes 104 and 105 and secure the output at the time of charging and discharging. The areas of the electrodes 104 and 105 referred to here are the plane areas of the surfaces facing each other. The areas of both electrodes 104 and 105 may be the same or different. In this example, the areas of both electrodes 104 and 105 are equivalent. The upper limit of the area of each of the electrodes 104 and 105 is, for example, about ^{8000 cm 2.}

<Electrode arrangement form>
In the present embodiment, as shown in FIG. 5, both electrodes 104 and 105 are arranged so as to have an overlapping region OA and a non-overlapping region SA between the positive electrode 104 and the negative electrode 105 in a plan view. FIG. 5 shows the arrangement state of the electrodes when the positive electrode 104 and the negative electrode 105 in the cell 100 are viewed through from the positive electrode 104 side. In the example of the electrode arrangement form shown in FIG. 5, the positive electrode is arranged. The 104 and the negative electrode 105 are arranged so as to be obliquely offset from each other. Specifically, the positive electrode 104 and the negative electrode 105 are arranged so as to be offset diagonally upward to the left and diagonally downward to the right from a state in which the positive electrode 104 and the negative electrode 105 are overlapped so as to coincide with each other. In this example, the areas of the positive electrode 104 and the negative electrode 105 are the same, and both the positive electrode 104 and the negative electrode 105 have a non-overlapping region SA. Further, the non-overlapping region SA of the positive electrode 104 and the non-overlapping region SA of the negative electrode 105 have the same area. In FIG. 5, for the sake of clarity, the overlapping region OA between the positive electrode 104 and the negative electrode 105 is shown by double hatching, the non-overlapping region SA of the positive electrode 104 is hatched upward to the right, and the non-overlapping region SA of the negative electrode 105 is shown. Each is shown by hatching that descends to the right.

In the example shown in FIG. 5, the case where the positive electrode 104 and the negative electrode 105 are arranged obliquely with respect to each other is illustrated, but the positive electrode 104 and the negative electrode 105 are arranged in the vertical direction (vertical direction) with respect to each other. It may be arranged so as to be offset in the left-right direction (horizontal direction).

Further, the areas of the positive electrode 104 and the negative electrode 105 may be different, and in that case, one electrode having a large area and the other electrode having a small area may be arranged so as to overlap with each other. In this case, the non-overlapping region SA is formed only on one of the positive electrode 104 and the negative electrode 105 having a large area, and the other electrode having a small area has only the overlapping region OA. In addition, when the areas of the positive electrode 104 and the negative electrode 105 are different, it is possible to arrange the electrode so that a part of the other electrode having a small area protrudes from one electrode having a large area. In this case, the other electrode having a small area can also have a non-overlapping region SA.

When the size of the electrode is small with respect to the recess 32o (see FIG. 3) of the cell frame 3 in which the electrodes 104 and 105 are housed, a protrusion protruding toward the electrode on the inner peripheral surface of the frame 32 in order to position the electrode. A portion (not shown) may be formed, or a protrusion (not shown) protruding toward the frame 32 may be formed on the outer peripheral surface of the electrode. The size of the protrusions may be large enough to support the electrode, and when the protrusions are provided on the outer peripheral surface of the electrode, they should be formed as small as possible so that the overlapping region does not increase too much. Alternatively, the electrodes can be positioned by inserting a separate positioning piece (not shown) between the inner peripheral surface of the frame body 32 and the outer peripheral surfaces of the electrodes 104 and 105. The positioning piece may be formed of a material having appropriate flexibility and resistance to an electrolytic solution (electrolyte resistance), for example, a material such as rubber, sponge rubber, or resin. Examples of the resin forming the positioning piece include expanded polyethylene, urethane foam, and expanded polystyrene.

As shown in FIG. 5, when at least one of the positive electrode 104 and the negative electrode 105 (both in this example) has a non-overlapping region SA, there is an unreacted electrolyte solution that has not reacted with the battery in the non-overlapping region SA. Will be done. This is because the non-overlapping region SA is a portion between the electrodes 104 and 105 that does not contribute to the battery reaction, so that the electrolytic solution flows in the non-overlapping region SA in an unreacted state. That is, when the pumps 112 and 113 are stopped and the flow of the electrolytic solution is stopped during a power failure of the power system L (see FIGS. 1 and 2), the unreacted electrolytic solution remains in a part of the cell 100. Become. Then, the unreacted electrolytic solution existing in the non-overlapping region SA diffuses into the overlapping region OA to cause a battery reaction between the electrodes 104 and 105, thereby pumping from the cell 100 (cell stack 2) in the event of a power failure. It is possible to supply the power required for starting 112 and 113. In this example, since both the positive electrode 104 and the negative electrode 105 have the non-overlapping region SA, an unreacted electrolytic solution exists in each non-overlapping region SA, and therefore, between the two electrodes 104 and 105. The battery reaction can be surely caused by. Further, since the areas of the non-overlapping regions SA in the positive electrode 104 and the negative electrode 105 are the same and the amount of the electrolytic solution flowing in the non-overlapping regions SA is the same, the battery reaction between the two electrodes 104 and 105 is sufficient. Can be woken up.

<Area ratio of overlapping area and non-overlapping area>
In the present embodiment, the total area of the non-overlapping region SA in the positive electrode 104 and the negative electrode 105 is 0.1% or more and 20% or less of the area of the overlapping region OA. Since the total area of the non-overlapping region SA is 0.1% or more of the area of the overlapping region OA, it is necessary to secure the amount of the electrolytic solution flowing in the non-overlapping region SA and to start the pumps 112 and 113 in the event of a power failure. It is easy to secure power. On the other hand, the larger the area ratio of the non-overlapping region SA (the total area of the non-overlapping region SA / the area of the overlapping region OA), the larger the ratio of the electrolytic solution flowing through the non-overlapping region SA, and the electrolytic solution flowing through the overlapping region OA Will be reduced. When the total area of the non-overlapping region SA is 20% or less of the area of the overlapping region OA, it is possible to secure the overlapping region OA that contributes to the battery reaction and suppress a decrease in output during charging / discharging. The total area of the non-overlapping region SA is preferably, for example, 0.2% or more and 15% or less of the area of the overlapping region OA.

{Effect of embodiment}
The cell 100, the cell stack 2, and the RF battery 1 according to the embodiment have the following effects.

"cell"
According to the cell 100 according to the embodiment, at least one of the positive electrode 104 and the negative electrode 105 has a non-overlapping region SA. As a result, when the pumps 112 and 113 are stopped during a power failure of the power system L, the unreacted electrolyte existing in the non-overlapping region SA diffuses into the overlapping region OA, resulting in discharge between both electrodes 104 and 105. , It is possible to discharge the electric power required to start the pumps 112 and 113. Therefore, the cell 100 of the embodiment can supply power to start the pumps 112 and 113 in the event of a power failure of the power system L.

The RF battery 1 including the cell 100 can start the pumps 112 and 113 by supplying electric power from the cell 100 to the pumps 112 and 113 even when the pumps 112 and 113 are not supplied with electric power from the outside. It will be possible. For example, even if the power system L fails when the RF battery 1 is discharged and the pumps 112 and 113 are stopped, the pumps 112 and 113 are driven by the undischarging electrolytic solution existing in the non-overlapping region SA in the cell 100. The power required to start up can be secured. Further, even if the self-discharge of the electrolytic solution progresses in the overlapping region OA between the electrodes 104 and 105 while the pumps 112 and 113 are stopped, the unreacted electrolytic solution existing in the non-overlapping region SA becomes the overlapping region OA. By diffusing, the electric power stored in the unreacted electrolytic solution can be discharged for a long period of time. Therefore, the time constraint from when the pumps 112 and 113 are stopped due to a power failure to when the pumps 112 and 113 are started can be relaxed.

When the total area of the non-overlapping region SA is 0.1% or more and 20% or less of the area of the overlapping region OA, it is easy to appropriately secure the amount of the electrolytic solution flowing in each region of the non-overlapping region SA and the overlapping region OA. It is easy to secure the electric power required for starting the pumps 112 and 113 at the time of power failure and to secure the output at the time of charging / discharging during normal operation.

When both the positive electrode 104 and the negative electrode 105 have a non-overlapping region SA as in the cell 100 of the embodiment, an unreacted electrolytic solution is present in the non-overlapping region SA of each of the electrodes 104 and 105. .. Therefore, the electrolytic solution can be reliably discharged between the electrodes 104 and 105, and the power required for starting the pumps 112 and 113 can be supplied in the event of a power failure to reliably start the pumps 112 and 113. It will be possible. Further, when the positive electrode 104 and the negative electrode 105 have the same area, a non-overlapping region SA having the same area is formed on both the positive electrode 104 and the negative electrode 105. Therefore, the electrolytic solution can be sufficiently discharged between the electrodes 104 and 105, and the electric power required for starting the pumps 112 and 113 can be sufficiently supplied in the event of a power failure.

Further, when the thickness of the positive electrode 104 and the negative electrode 105 is 0.05 mm or more, it is easy to sufficiently secure the amount of the electrolytic solution flowing in the non-overlapping region SA. Therefore, it is easy to secure sufficient electric power required to start the pumps 112 and 113 in the event of a power failure. Since the areas of the positive electrode 104 and the negative electrode 105 are 250 cm ² or more, it is easy to sufficiently secure the areas of the overlapping region OA and the non-overlapping region SA, and the amount of the electrolytic solution flowing in each region is sufficiently secured. easy. Therefore, it is easy to secure the output at the time of charging / discharging and sufficiently secure the electric power required for starting the pumps 112 and 113 at the time of a power failure.

《Cell stack》
According to the cell stack 2 according to the embodiment, by providing the cell 100 of the above-described embodiment, it is possible to supply electric power for starting the pumps 112 and 113 in the event of a power failure of the power system L. The cell stack 2 includes a plurality of cells 100, and it is easy to secure the electric power required to start the pumps 112 and 113 by the unreacted electrolytic solution existing in the non-overlapping region SA in each cell 100. Is. Therefore, it is possible to sufficiently supply the electric power required for starting the pumps 112 and 113 from the cell stack 2.

《RF battery》
According to the RF battery 1 according to the embodiment, by providing the cell 100 or the cell stack 2 of the above-described embodiment, the power required to start the pumps 112 and 113 from the cell 100 or the cell stack 2 in the event of a power failure of the power system L. Can be supplied, and the pumps 112 and 113 can be started. Therefore, the RF battery 1 of the embodiment can restart the operation by itself when the power system L has a power failure.

[Test Example 1]
RF batteries (test bodies A to C) having different arrangement forms of the positive electrode and the negative electrode in the cell were assembled, and a pump start test was performed using each RF battery.

A cell stack was prepared by laminating a plurality of cell frames, positive electrodes, diaphragms, and negative electrodes in this order to form a laminated body. Carbon felt electrodes of the same shape and size were used for the positive electrode and the negative electrode. The positive electrode and the negative electrode used have a rectangular planar shape, the same area and thickness, an area of 250 cm ² , and a thickness of 0.3 mm. The number of stacked cells in the cell stack was set to 5.

In this test, in each cell constituting the cell stack, the total area of the non-overlapping regions of the positive electrode and the negative electrode is 0.1%, 20%, 0.05%, and 0% of the overlapping region area. Three types of cell stacks in which electrodes were arranged were prepared. Then, a circulation mechanism for circulating the electrolytic solution was attached to each cell stack, and test bodies A to C of the RF battery were assembled. Here, when the total area of the non-overlapping regions is 0% of the area of the overlapping regions, it means that the entire surfaces of both electrodes overlap each other.

In the test method, the RF battery of each test piece was charged and then discharged, the pump was stopped at the time of discharge, and power was supplied from the cell stack to the pump while the pump was stopped, and it was examined whether the pump was started. Table 1 shows whether or not the pump can be started. The power required to start the pump used is 5W. In Table 1, the case where the pump can be started is shown as "A", and the case where the pump cannot be started is shown as "B".

From the results in Table 1, it was confirmed that if the total area of the non-overlapping areas is 0.1% or more of the area of the overlapping areas, the electric power for starting the pump can be supplied.

{Use of embodiment}
The redox flow battery cell and the redox flow battery cell stack according to the embodiment can be suitably used for the redox flow battery.

1 Redox flow battery (RF battery)
L Power system C AC / DC converter 2 Redox flow battery Cell stack (cell stack)
3 Cell frame 31 Bipolar plate 32 Frame body 32o Recess 33, 34 Liquid supply manifold 35, 36 Drainage manifold 33s, 34s Liquid supply slit 35s, 36s Liquid drainage slit 37 Seal member 38 Seal groove 100 Redox flow battery cell (cell)
101 diaphragm 102 positive electrode cell 103 negative electrode cell 100P positive electrode circulation mechanism 100N negative electrode circulation mechanism 104 positive electrode electrode 105 negative electrode electrode 106 positive electrode electrolyte tank 107 negative electrode electrolyte tank 108, 109, 110, 111 conduit 112, 113 pump 200 sub Stack 210 Supply / discharge plate 220 End plate 230 Tightening mechanism OA Overlapping area SA Non-overlapping area

Claims (6)

A redox flow battery cell including a positive electrode, a negative electrode, and a diaphragm interposed between the positive electrode and the negative electrode.
It has an overlapping region in which the positive electrode and the negative electrode overlap with each other via the diaphragm, and a non-overlapping region in which both the positive electrode and the negative electrode do not overlap with each other via the diaphragm.
The total area of the non-overlapping regions is 0.1% or more and 20% or less of the area of the overlapping regions .
Redox flow battery cell. The redox flow battery cell according to claim 1 , wherein the positive electrode and the negative electrode have the same area. The redox flow battery cell according to claim 1 or 2 , wherein the positive electrode and the negative electrode have a thickness of 0.05 mm or more. The redox flow battery cell according to any one of claims 1 to 3 , wherein the area of the positive electrode and the negative electrode is 250 cm ^{2 or more.} A plurality of redox flow battery cells according to any one of claims 1 to 4 are stacked and provided.
Redox flow battery cell stack. The redox flow battery cell according to any one of claims 1 to 4 , or the redox flow battery cell stack according to claim 5 is provided.
Redox flow battery.

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